Process of air-blowing asphalt



l aten'ted Nov. 4, 195% PATENT OFFICE.

' PROCESS OF AIR-BLOWINCASPHALT 4 .Ioseph Carl Roediger, Brooklyn, N Y., ass'i gnoi" to Standard Oil Development Company, a corporation of Delaware No Drawing. Application January 3, 1949, Serial No. 69,031

3'Claims. (crust-44in.-

The object of this invention is a process of air blowing asphalt tomodify itfto one having certain types of asphalt paving mixtures, etc'., re

quire the heating of the asphalt'to a fluid [condition and therefore it"is very desirable that the fiashfpoint of the asphalt being'used be relatively high, preferably above 500 F., so that the manufacturing operation can be conducted with safety and freedom from flash fires.

Heretofore the production of asphalts havin a satisfactory high flash point and other desirable properties has been a serious problem. The flash point of the asphalts produced by direct. distillation to a large degree is dependent upon the type of compounds which exist in the crude oil'as delivered from the well. For this reason, the asphalts obtainable from certain crude oils are too low in flash point to make them suitable for all general applications. One procedure followed in preparing asphalts of desirablecharacteristics from crude petroleum oil which pro duces a low flash asphalt is to reduce this by conventional means to a high flash point, high softening point asphalt bottoms. In other words, remove the major portion of the low boiling oils. These high softening point asphalt bottoms may then be blended with a high flash oil obtained in the processing of a crude oil of different origin. In this manner the final blended asphalt will have a higher flash point than that which is directly obtainable from the original asphaltic crude.

While this procedure will produce asphalts of satisfactory characteristics and having satisfactory flash points, certain problems are encountered. One difficulty is that it is generally uneconomical since double processing is required and two crudes must be handled.

According to this invention it was found that when selected silicones are added to the asphaltic composition the flash point of the asphalt is materially raised. The silicones used have a formula:

[Rmsioykli wherein R may be an alkyl or aryl group, m may be an integer of 1, 2 or 3, yis a variable integer whose value depends on m, the valency of Si beh1g4, and a: is an integer greater than 2. Silicones having a viscosity at 77 F. of-'100 to 1000 centistokes a'nd flash of BOW-640 F. are used. For example; it is preferred to use a silicone oil having a viscosity of; about 350 centistokes at 77 F. preferably from .0005 to 005% of the silicon oil based on the asphalt. 1

My invention may be readily understood by the following examples illustrating embodiments of the same.

Example 1 7 Various percentages of a silicone oil polymer were used with Colombian and Venezuelan as phalts of the 80/100 penetration 77 F./100g./5 seconds grade commonly used for highway pavement construction. The results secured are as follows:

Asphalt Compositions Asphalt Crude Basc Colombian Venezuelan Percent Methyl Polysiloxane Polymer 0 0. 001 r 0 0.001

Spec. Grav 60 F 1.009 1.007 1.025 1 023 Flash (COO), T... 605 670 595 700+ Softening Point, "F 118 116 117 117 Penetration, 77 F./100 5 84 83 81 85 Penetration, 32 F./ g./5 seconds. 18 l7 l9 l9 From'the above it is apparent that the flash points of the respective asphalts were increased to an appreciable degree without significant change in the other properties, aside from a slight reduction in specific gravity.

Eacamplev 2 In other experiments various percentages of this polymer were added to Colombian and Venezuelan asphalts of the type used by the roofing industry for the saturation of the felt sheet forming the base for roll roofings. The results of these experiments are tabulated below:

In the case of the Colombian asphalt polymer mixtures, maximum flash point increase is obtained within the range of 0.0005 to 0.001% added siloxane polymer. In other words, the optimum 3 increase in flash point occurs within a rather restricted range of polymer concentration.

Asphalt-silicone oil mixtures of this type can be used for the more efficient saturation of roofing felt, Celotex-type board and other fibrous boards since the higher flash point of this mixture permits operation with safety at higher saturating temperatures. Likewise, the higher operating temperature now possible permitsfthe'use of saturants of higher consistency than heretofore.

Example 3 F., as shown in column A of the followin tabula tion.

Lagunillas Flux (465 F. Flash) Percent Silicone Oil Polymer 0.0 0. 001

I. Flux Bose A 13 Flash (000), F 465 505 Fire 000), "F 525 5st Furol Viscosity at 165 161 II. Roofers Flux Oxidized from (I) A B Flash (COO) "F 475 520 Fire (CO0), 13 525 575 Softening Point, "F 109 107 Penetration, 77 F./l00 g./ seconds. 172 182 Penetration, 32 F./100 g./5 seconds... 73 65 III. Coating Asphalt Oxidized from (I) A B Flash (000), F .1 500 580 Fire (000), F 560 605 Softening Point, "F 221 226 Penetration, 77 F./100 g./5 seconds 18' 18 Penetration, 32 F./l00 g./5 seconds 13 13 In the above table the roofers flux composi tions, item II, were made by conventional oxi-d-a:

by oxidation to a higher softening point asphalt from flux base, item I. In both the A and B series, the oxidations were carried out under identical conditions employing a 450 F. :10 F. for the oxidation to Roofers Flux and a 450/ 475 F; temperature when air blowing the Roofer's Flux to high SP Coating asphalt. These compositions were prepared using flux base without polymer addition for the A series and with 0.001 silicone polymer for the B series.

The above example also shows that the efiectiveness of the silicone oil addition is not decreased when the flux-polymer composition is subjected to oxidation at elevated temperatures for the production of higher softening point oxidized asphalts.

What is claimed:

1. In the process of air-blowing asphalt, the improvement. which comprises conductin said air-blowing in the presence ofan amount of a methylpolysiloxane suflicient to substantially increase the flash point of said asphalt.

2 In the process of air-blowing asphalt, the improvement which. comprises conductin said air-blowing. in the presence of about 0.0005% to 0.005%. of a methylpolysiloxane to substantially increase the flash point of said asphalt.

3 In the process of air-blowing asphalt, the improvement. which comprises heating said asphalt to a temperature of about 450 F. andconducting said air-blowing in the presence of an amountof a methylpolysilox-ane sufiicient to substantially increase, thefiash point of said asphalt.

JOSEPH CARL ROEDIGER.

REFERENCES CITED Thefollowing references are of reeord'in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,258,218 Rochow Oct. 7, 1941 2,416,504 Trautman et a1 Feb. 25, 1947 OTHER REFERENCES Qil and Gas Journal, October 6, 1945, pages 87 wer Dow, Corning Silicone Note Book Flui d Series No. 3, September 1943, page 11. 

1. IN THE PROCESS OF AIR-BLOWING ASPHALT, THE IMPROVEMENT WHICH COMPRISES CONDUCTING SAID AIR-BLOWING IN THE PRESENCE OF AN AMOUNT OF A METHYLPOLYSILOXANE SUFFICIENT TO SUBSTANTIALLY INCREASE THE FLASH POINT OF SAID ASPHALT. 